This disclosure generally relates to non-destructive inspection equipment and methods, and relates more particularly to methods and apparatus for inspecting barrel-shaped structures made of composite material.
Non-destructive inspection (NDI) of structures involves thoroughly examining a structure without harming the structure or requiring significant disassembly. Inspection may be performed during manufacturing of a structure and/or after a structure has been put in service to determine the condition, quality, or structural state of the structure.
The production manufacturing of a large composite structure for an active airplane program needs to be done at a rate that meets schedule commitments. Non-destructive inspection of primary structure is a necessary part of the manufacturing process and must be done at a rate capable of keeping up with the published schedule.
For example, it is known to fabricate barrel-shaped fuselage sections made of composite material on an assembly line with high through-put. The finished fuselage sections need to undergo NDI at a high rate. Some existing solutions for inspecting barrel-shaped fuselage sections are large, expensive multiple-axis robotic systems which move ultrasonic transducer arrays over the outer mold line (OML) of the fuselage section using encoded rails and end effectors guided to follow pre-programmed paths.
In addition, high-speed non-destructive inspection of stiffeners (stringers) on the inside of many composite airplane fuselage sections is desirable in order to maintain the manufacturing rate. One existing solution involves rolling the barrel-shaped fuselage section in a rotating tool frame that allows each stiffener being inspected to be under a robotic crawler, so gravity is not an issue, and the stiffener crawlers holding multiple ultrasonic transducer (UT) arrays can crawl on a relatively horizontal surface.
There is a need for improvements in systems and methods for non-destructive inspection of barrel-shaped workpieces (such as fuselage sections that may include internal stiffening elements) that facilitate a high rate of production.